A nail file does sound rather harsh. Maybe for getting off big chunks of corrosion, if that's what you're dealing with. I collect old 8-bit Nintendo games. I got a copy of the Legend of Zelda off ebay and the contacts were all green, chunky, and corroded. I put on a nice layer of Deoxit, let it sit overnight, then went at it with some q tips and a bit more Deoxit until I was down to clean, shiny copper.
6/20/12 at 8:22am